The vomeronasal system is a major direct source of exteroceptive information to the limbic system. In the past ten years the functional significance of the vomeronasal system as a system separate from the olfactory system has been established. In snakes the vomeronasal system is consistently well developed and structurally more prominent than the main olfactory system. In addition, snakes use their vomeronasal systems in a variety of situations including detection of prey odors and detection of conspecific chemical signals used in courtship, aggregation and habitat selection. Current research emphasis is directed at understanding the interrelationship between the olfactory and vomeronasal systems using behavioral and electro-physiological approaches, and determining the chemical basis of differential stimulation of the vomeronasal and olfactory systems. A better understanding of the roles of the chemical senses in species typical behaviors should result in establishment of some principles of limbic system functioning.